gas exchange

Question 1

mechanism of breathing in

Answer 1

1.diaphragm contracts and flattens
2.external intercostal muscles contract
3.internal intercostal muscles relax
4.ribcage pulled upwards and outwards
5.volume inside the thorax increases and pressure decreases
6.air rushes into the lungs

Question 2

mechanism of breathing out

Answer 2

1.diaphragm relaxes and retuns to normal dome shape
2.external intercostal muscles relax
3.internal intercostal muscles contract
4.ribcage pulled inwards and downwards
5.volume inside the lungs decrease and pressure increase
6.air moves out of lungs

Question 3

adaption of alveoli

Answer 3

1.have large surface area to increase rate of diffusion
2.have thin walls which provide short diffusion distance
3.moist to dissolve gases

Question 4

how lungs are protected against infection

Answer 4

1.respiratory tract is lined by ciliated epithelium with goblet cells
2.the goblet cell secretes mucus which is thick and sticky to trap bacteria.
3.cilia pushes the mucus out

Question 5

regulation of carbon dioxide content in blood

Answer 5

1. during exercise rate of respiration increases, so level of co2 in blood increases
   2.co2 dissolves in the plasma forming a weak acid
   3.chemoreceptors in the medulla of the brain, aorta, and carotid artery detect the change in ph of blood
   4.chemoreceptors send impulse to the respiratory center in the brain, which stimulates the breathing rate to increase
   5.more carbon dioxide passes from the blood to the lungs
   to be exhaled

Question 6

oxygen debt

Answer 6

1.during exercise muscles run short of oxygen
2.muscles respire anaerobically resulting in the formation of lactic acid
3.lactic acid is transported to the liver

Question 7

consequences of smoking to the lungs

Answer 7

1.tar destroys the cilia and increases mucus secretion which is not swept away. bacteria in mucus causes bronchitis which blocks normal air flow causing difficulty in breathing and coughing
2.smoke damages the walls of the alveoli reducing surface area for gas exchange reducing the oxygen levels in blood this is called lung emphysema
3.tar causes lung cancer

Question 8

consequences of smoking on circulatory system

Answer 8

nicotine: raises blood pressure->risk of heart attack
carbon monoxide: binds to haemoglobin
->carboxyhaemoglobin so red blood cells carry less O2